In one system for the production of glass fibers, glass is melted from batch or cullet in a furnace and then delivered in its molten state to the fiberizers and feeders by means of a channel or series of interconnecting channels or troughs. The lengths of these channels can be one hundred feet or more. With such massive lengths, the change in length of the channel as it is heated from room temperature, at which it was fabricated, to its operating temperature, generally in the vicinity of 2000.degree. F., is rather substantial.
Historically, the channels were fabricated from refractory bodies stacked and/or interconnected to form the channel to contain the flow of molten glass therein. To accommodate the substantial longitudinal growth of the channel due to the change in temperature between fabrication and operation, expansion joints, that is, gaps between the refractory bodies were provided at various points along the length of the channel. For example, a gap of about one half inch is provided about every eight to ten feet in a conventional installation.
In theory, with both ends of the channel held relatively fixed, the proper number and size of gaps or expansion joints can be calculated and provided which will then close upon heating of the channel to its desired operating temperature. Unfortunately, practical application of the theory is not always perfect. Some of the gaps fail to close sufficiently thereby permitting molten glass to leak therefrom.
The present invention provides a molten glass delivery channel fabricated without expansion joints while still accommodating its lengthwise thermal expansion.